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Day 18 (July 13, 2011) A Trip to Africa’s Largest Lake

July 13, 2011

Lake Victoria comes into view as we enter on to the Homa Peninsula.

Today’s our big trip. As I noted on July 9, one reason my four research colleagues from China are visiting is to explore the deposits of the Homa Peninsula in western Kenya, and to discuss how they can contribute to research we plan on the peninsula in the coming years. The Homa Peninsula is the landmass immediately south of the Winam Gulf, an eastern arm of Lake Victoria that protrudes into western Kenya.

Our mini-expedition consisted of the four from China, also Muthengi Kioko (who’s a member of our crew and an excellent driver and car mechanic), and myself. At least that’s the group that left Olorgesailie and navigated the morning traffic into Nairobi. In the city, we met Dr. Tom Plummer, a professor of anthropology from Queens College - City University of New York. Tom and I have had a long association from when he was my PhD student more than 20 years ago. He co-directs the Homa Peninsula projects with me, and has been the leader of that research enterprise over the past decade.

We also met Mr. Blasto Onyango, who heads the fossil preparation lab at the National Museums of Kenya. Blasto grew up about 5 miles from some of our main digs on the Homa Peninsula, and knows the roads, paths, and gullies of the area like the back of his hand. Since he grew up speaking Luo, the local language, he’s also a big help as we meet villagers and curious onlookers during our search for fossils and as we stand around discussing the geology.

Mount Homa, in the distance, gives the Homa Peninsula its name. As you can imagine from its shape, Mt. Homa is an ancient volcano that was active between about 8 and 2 million years ago.

The eight of us piled into our big Land Cruiser, the one vehicle large enough to fit us all along with food, water, and luggage. The trip took a little under 8 hours, including a stop for lunch near a town called Narok. By the end of our journey, I couldn’t help but be bowled over, once again, by the size and majesty of Lake Victoria, Africa’s largest lake. I last took a research trip here in 2006, and today it was marvelous having the vast lake panorama come into view as the slanting light of the late afternoon sun shimmered over its surface.

Close to where the lake laps up on Kenya’s shore, the ancient sediments are exposed by erosion. They preserve the fossil remains of organisms dating back a little older than 6 million years – an extraordinary time in our evolutionary history. Fossils from other places in Africa and genetic studies indicate that 6 million is near the time of the evolution of our oldest direct ancestor. That oldest ancestor came from a population that split off from the common ancestor our species shared with chimpanzees. That’s how evolution works, creating diverse species as populations change and become separated from one another over time. So the 6-million-year-old deposits we’ll be inspecting over the coming days provide a record of fossils and habitats at the time when, somewhere in Africa, the human group of species began, of which we (Homo sapiens) are the last remaining one.

The beauty of the largest tropical lake in the world, at sunset. Many local people make a living by fishing from small, well-crafted sail boats.

There’s also a lot more to the layers of sediment of the Homa Peninsula. Tom’s digs over the past ten years, for instance, preserve stone tools of some of the oldest human ancestors to live in a grassland habitat, sometime between 1.95 and 2.0 million years ago. The name of that site is Kanjera South, and there’s still a lot to learn from digging there and at other sites in the area that are probably the same age. In fact, the Homa Peninsula is dotted all over by eroded gullies and hillsides, little chapters that tell the 6-million-year story of this region up to the lives of Late Stone Age peoples of just a few thousand years ago.

Chenglong, Huaiyu, Yongxin, and Zhengtang are excited to poke around with us and see what’s here – and to figure out how their expertise in dating sediments and analyzing ancient environments can further our understanding.